The present invention relates to a hydraulic control valve arrangement for controlling the amount of pressure fluid flowing to at least one consumer, in which the valve member of a first valve selectively controls the flow of pressure fluid to at least one consumer or from the latter to a return passage and forms a variable throttle between a pressure fluid inlet passage and the consumer passage connected to the consumer, in which the throttle causes a pressure difference, and in which the pressure difference or pressure drop may be maintained substantially constant by a bypass passage between the inlet passage and the return passage in which a second valve member is arranged which is biased by a spring to a closed position and by the aforementioned pressure difference produced by the variable throttle to an open position.
In a known hydraulic control arrangement of the aforementioned kind, the second valve member is biased by a spring to the closed position in which the pretension of the spring is adjustable by a hydraulically movable piston. In this way it is possible to obtain a very small circulation pressure when the first valve is closed and in which by lacking load pressure the aforementioned piston assumes an end position in which the pretension of the spring reaches its minimum value. On the other hand, when the pretension of the spring at prevailing load pressure increases, the hydraulic control valve arrangement can be used for considerably higher flow speeds. This known arrangement has, however, the disadvantage that the transition from the lower to the higher pressure drop will not occur in a gradual manner, but abruptly. In addition, this known arrangement is relatively complicated since it needs for tensioning the spring an additional hydraulically actuated piston.